The present invention relates to a dispersion composition and a method for producing the same. More particularly, it relates to a dispersion composition which can be utilized in the technical fields where a particulate material insoluble in organic solvent is dispersed and used, for example, the field of paint, printing ink, liquid developer (wet toner) or ink jet ink where a pigment or a dye as a particulate material is dispersed and utilized, the field where a medicine as a particulate material is dispersed and utilized, and the field where a catalyst or a polymerization initiator as a particulate material is dispersed and utilized, and to a method for producing the same. The present invention further relates to a dispersion composition utilizable also in the field of coloring materials comprising a polymeric compound in which a particulate material is included by drying, such as dry toners, powdered paints, and plastics, and to a method for producing the same.
Hitherto, in the field of utilizing pigments or dyes which are particulate materials insoluble in organic solvents, a fine dispersion of particles has been made resulting in improved storage stability. For example, British Patent No. 2001083 discloses the use of a specific polyester amine as a pigment dispersant in paints or inks.
Furthermore, JP-A-8-30040 discloses a liquid developer prepared by dispersing in a non-aqueous solvent an urethane-based microencapsulated colored resin particle containing a pigment or a dye.
Moreover, JP-A-3-160464 discloses a solid self-dispersion type coloring material comprising a mixture of a pigment or a dye and a self-dispersion type graft polymer which forms particles upon self-dispersing in a high insulation carrier liquid, and mentions use of silicone-based graft polymers.
However, in the dispersion compositions using general dispersion stabilizers and pigment dispersants disclosed in the above British Patent No. 2001083, the type of organic solvent or pigment used is limited. Moreover, stabilization of the dispersion has been attempted by steric repulsion of the resins, however since the amount of electric charge generated at the surface of the pigment is small, in the case of dilute pigment dispersion, sedimentation occurs when stored for a long time and thus it lacks dispersion stability.
Furthermore, the solid self-dispersion type coloring material using urethane-based microencapsulated colored resin particles or self-dispersion type graft copolymers have the problem of sedimentation in long-term storage when they are used for liquid developers or ink jet inks because of their large dispersion particle diameter.
Moreover, the polymer toners have a large particle diameter because they are obtained by dispersing a reactive silicone monomer, an isocyanate and a coloring material and then polymerizing them, and the silicone-containing polymer used for the improvement of dispersibility dissolves in the organic solvent in the ink to cause sedimentation of toner particles in the ink.